EVSC 1010 Lecture 6: Lecture 6 - Glaciers
24 Oct 2016
School
Department
Course
Professor
Document Summary
A glacier is a massive, long-lasting, moving mass of compacted snow and ice. Earth orbital variations may explain the temperature oscillations and glacial advances and retreats: varies in three ways: Elliptical shape of orbit changes over a cycle of ~ 100,000 years. Tilt of the earth"s axis of rotation oscillates by about 2 over ~ 41,000 years. Earth"s axis complete full cycle of procession ~ 26,000 years. Maximum extent of continental glaciers in north america during the last glacial advance, ~ 18,000 years ago. New fallen snow goes through several stages to form glacial ice: snowflake granular snow firn glacier ice. Basal slip: the entire glacier slides over the bedrock: moving in unison. Plastic flow: the ice flows as a viscous fluid: flows as a stream, velocity greater in the center so it moves faster than the ones on the outside. Region where more snow falls during the winter than melts during the summer is called the zone of accumulation.
